ClickHouse Packs a HyperLogLog Rank Into Five Bits
ClickHouse’s CompactArray stores sub-byte values in a bitset and reads them through an unaligned 16-bit window, so a HyperLogLog rank costs 5 or 6 bits per bucket.
ClickHouse’s CompactArray stores sub-byte values in a bitset and reads them through an unaligned 16-bit window, so a HyperLogLog rank costs 5 or 6 bits per bucket.